feel high watermark," I said. "Try, Jerry."
We felt all the way around the sides of the cave toward the bottom, but as far as we could tell there was no sea-weed at all.
"That does n't help us much," Jerry said, "because we don't know whether the tide is really full now and has covered it, or whether it just does n't grow here."
We curled our feet under us and waited. We could hear the water sloshing around very close to us. Once when I put out my hand it went right into a cold pool. It was then that Jerry had a most wonderful idea. I heard his knife snap open again and asked him what it was this time.
"If I take the crystal off my watch," he said, "I can feel where the hands are."
I heard the little clicking pop that the front of a watch makes when you pry it off, and I knew he was feeling the hands very gently.